In general most of the android phones we use google Gboard app for text typing. We may not know there is separate app for this since this is default one. Some times this app has stopped working and keep getting the pop up like this. Even it we give OK it will not go .

unfortunately_gboard_stopped

This because any of the google default services got an update and this is  not compatible with Gboard. To stop this just go to

Settings-->
                   Apps -->
                                   GBoard

Now click on Force stop and uninstall the updates.  This will stop the pop up keep coming. Now there could be a case you may see keyboard in mobile. If you go for contact search it will ask to use voice search. To fix this go to playstore and get the latest Gboard app from store.